US4200884A - Signal processing system for a solid state television camera - Google Patents

Signal processing system for a solid state television camera Download PDF

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Publication number
US4200884A
US4200884A US05/915,253 US91525378A US4200884A US 4200884 A US4200884 A US 4200884A US 91525378 A US91525378 A US 91525378A US 4200884 A US4200884 A US 4200884A
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Prior art keywords
signal
color
pulse
solid state
circuit
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US05/915,253
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English (en)
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Fumio Nagumo
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Sony Corp
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Sony Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/80—Camera processing pipelines; Components thereof
    • H04N23/84—Camera processing pipelines; Components thereof for processing colour signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/10—Circuitry of solid-state image sensors [SSIS]; Control thereof for transforming different wavelengths into image signals
    • H04N25/11—Arrangement of colour filter arrays [CFA]; Filter mosaics

Definitions

  • the present invention relates to a television camera using a solid state image sensor such as a CCD (charge-coupled device), and particularly to a signal processing system for the solid state television camera.
  • a solid state image sensor such as a CCD (charge-coupled device)
  • CCD charge-coupled device
  • a video signal from the image pickup tube is processed through a well-known gain control circuit, phase shifting circuit and so on, so that the resultant processed video signal is ready for use as a standard television signal.
  • the analog-signal gate circuit can be used instead of the sample-hold circuit.
  • the basic operation of this system includes a gain control means.
  • a typical example of this gain control means is represented by an embodiment for a white balance control system of a solid state color camera.
  • a direct NTSC conversion system is achieved by applying the phase shifting operation and gain control operation to a dot-sequential color television signal directly obtained from the solid state color television camera.
  • FIG. 1 is a view used for explaining one example of a solid state image pickup device
  • FIG. 2 is a waveform diagram used for the above explanation
  • FIG. 3 is a plan view showing one example of a color coding filter
  • FIG. 4 is a block diagram showing one example of a signal processing system for a solid state television camera of this invention
  • FIG. 5 and FIG. 6 are vector diagrams used for explaining this invention.
  • FIGS. 7A through 7E are waveform diagrams used for explaining this invention.
  • FIGS. 8A through 8O are waveform diagrams used for explaining the circuit of FIG. 4,
  • FIG. 9 is a block diagram showing another example of a signal processing system for a solid state television camera of this invention.
  • FIGS. 10A through 10I are waveform diagrams used for explaining the circuit of FIG. 9, and
  • FIG. 11 is a block diagram showing a further example of a signal processing system for a solid state television camera of this invention.
  • FIG. 1 is composed of a photo sensitive area 1 defined by m number of picture elements in the horizontal direction of a picture screen and n number of picture elements in the vertical direction to provide a total of mn picture elements.
  • a similarly arranged but optically shielded storage area 2 is provided as well as an output shift register 3, each for m number of bits.
  • This solid state imaging device is operated in such a manner that an object to be televised is picked up by a solid stage image sensor which generates electric charges in the photo sensitive area 1 during each vertical scanning interval T S , and these electric charges are then sequentially transferred to the storage area 2 line by line in accordance with n number of transfer pulses C A .
  • These pulses are shown in FIG. 2 and follow a marker signal M T indicating transfer start within the next vertical retrace interval T B which includes a vertical synchronizing signal S V .
  • the charges for every line are sequentially transferred to the output shift register 3 by a transfer pulse C B at a time after a horizontal synchronizing signal S H within each horizontal retrace interval.
  • these charges are adapted to be read out at its output terminal in a series manner for every m number of bits by a transfer pulse C O during the respective horizontal scanning interval.
  • the transfer pulses C A , C B and C O are composed of 3-phase clock pulses C A1 , C A2 and C A3 ; C B1 , C B2 and C B3 ; and C O1 , C O2 and C O3 , respectively.
  • a color coding filter as shown in FIG. 3 is disposed in front of the photo sensitive area 1 in case of a color camera system.
  • the color coding filter is formed with three kinds of striped filters each of the same width.
  • Striped filter F R is for passing therethrough red color light
  • striped filter F G is for passing therethrough green color light
  • striped filter is F B for passing therethrough blue color light.
  • the strips F R , F G and F B are arranged in a sequentially repeated manner as F R , F B , F G , F R , F B , F G . . . , each corresponding to one column of the picture elements of the image sensing area 1.
  • a dot-sequential color signal comprising an output signal E R for red color light, an output signal E G for green color light, and an output signal E B for blue color light which are sequentially repeated as E R , E B , E G , E R , E B , E G . . . .
  • FIG. 4 shows one example of this invention in which such a dot-sequential color signal is caused to be coincident with an NTSC color television signal without using a decode-encode system.
  • reference numeral 4 designates a solid state color pickup device as described above.
  • a synchronizing signal from a signal generator 5 is supplied to a timing signal generator 6 which derives therefrom a clock pulse, which is fed to the solid state color pickup device 4.
  • the device 4 In response to this clock pulse, the device 4 generates a dot-sequential color signal, which is fed through an amplifier 7 to a sample-hold circuit 8.
  • the timing signal generator 6 also produces a sampling pulse S A having a frequency which is three times the frequency f s of the dot-sequential color signal.
  • This sampling pulse S A is applied to the sample-hold circuit 8 where the red, green and blue color signals E R , E G and E B are sampled and held.
  • These signals are gamma ( ⁇ )--corrected by a ⁇ --correction circuit 9.
  • the ⁇ -corrected signal from the circuit 9 consists of, as shown in FIG. 7A, a luminance signal component E Y which mainly occupies the low frequency range, and a modulated carrier component E C which is composed of chrominance signal components E R , E B and E G each having the same carrier frequency f s relative to three primary colors.
  • This composite signal E M is expressed as follows:
  • E R , E B and E G represent peak values of respective primary color signals of the dot-sequential color signal E M .
  • the modulated carrier component E C is shown by vectors R, B and G which have the same amplitude but adjacent components differ in phase by 120° from each other.
  • a chrominance carrier component E CN of an NTSC color television signal E N is shown in FIG. 6 and expressed as follows:
  • the NTSC color television signal E N is a little different from the dot-sequential color signal E M .
  • this invention is applied to a circuit wherein the dot-sequential color signal E M obtained as mentioned above is converted directly into an NTSC color signal.
  • the dot-sequential color signal E M (FIG. 8A) from the ⁇ -correction circuit 9 is fed to a band pass filter 10 having a pass characteristic such as shown in FIG. 7C to drive therefrom a high frequency component E YH of the luminance signal, which is applied to an adder 11.
  • the dot-sequential color signal E M from the ⁇ -correction circuit 9 is also supplied to signal processing circuits 12 and 16, respectively.
  • the timing pulse T P is synchronized with the pulse S A and occurs at a time corresponding to the edge of the red color signal component E R . This timing pulse T P is fed to both of the processing circuits 12 and 16.
  • the processing circuit 12 produces a signal such that the composing ratio of red, green and blue color signals satisfies equation (4)
  • the processing circuit 16 produces a signal such that the composing ratio of red, green and blue color signals and their phases satisfy the equation (3).
  • the dot-sequential color signal E M is supplied to an analog-signal gate circuit 121.
  • the timing pulse T P from the timing signal generator 6 is applied to monostable multivibrators 122R, 122B and 122G, respectively, to trigger them at its falling edge.
  • the multivibrator 122R supplies a pulse M R1 which rises at the falling edge of the timing pulse T P and occurs at a position in time within the red color signal E R as shown in FIG. 8C.
  • the multivibrator 122B supplies a pulse M B1 which falls at a position in time within the blue color signal E B as shown in FIG. 8E
  • the multivibrator 122G supplies a pulse M G1 which falls at a position in time within the green color signal E G , in this case, at the edge of the green color signal E G as shown in FIG. 8G.
  • these pulses M R1 , M B1 and M G1 are respectively applied to monostable multivibrators 123R, 123B and 123G to trigger them by respective the falling edges thereof to derive therefrom pulses P R1 (FIG. 8D), P B1 (FIG. 8F) and P G1 (FIG. 8H), respectively, having pulse widths of ⁇ R , ⁇ B and ⁇ G .
  • the apperture centers of these pulses are not changed and correspond to the center positions of the respective intervals of red, blue and green color signals.
  • the widths of the output pulses of multivibrators 123R, 123B and 123G are so selected that their aperture centers maintain their phases of sequential 120°-phase shifts.
  • the pulses P R1 , P B1 and P G1 are then applied to an OR circuit 124 to derive therefrom a gate signal G Y (FIG. 8I), which is supplied to the analog-signal gate circuit 121 to open it at an interval during which the signal G Y is in a state of "1".
  • the gate circuit 121 produces a signal in which the color signals E R , E B and E G are composed in a ratio of 0.17:0.06:0.33.
  • This signal is supplied to a low pass filter 13 having a pass band characteristic as shown in FIG. 7B to derive therefrom a low frequency component E YL of the luminance signal E Y .
  • This low frequency component E YL is composed of red, blue and green color low frequency components E RL , E BL and E GL in the following ratio:
  • the above ratio is substantially the same as the component ratio of the luminance signal in the NTSC color television signal.
  • the thus obtained low frequency luminance signal component E YL is fed to the adder 11 where it is added with the high frequency luminance signal component E YH from the band pass filter 10 to obtain a luminance signal E YN converted into the NTSC color television signal.
  • This signal is supplied through a processor amplifier 14 to an amplifier 15.
  • the dot-sequential color signal E M is fed to an analog-signal gate circuit 161.
  • the timing pulse T P is supplied to monostable multivibrators 163R, 162B and 162G, respectively.
  • the multivibrator 162B produces a pulse M B2 which falls within a portion in time of blue color signal E B as shown in FIG. 8K.
  • the multivibrator 162G produces a pulse M G2 (FIG. 8M) which is fed to a monostable multivibrator 163G to derive therefrom a pulse P G2 (FIG.
  • the pulses P R2 , P B2 and P G2 are then fed to an OR circuit 164 to derive therefrom a gate signal G C (FIG. 8O), which is supplied to the analog-signal gate circuit 161 to open it at an interval during which the signal G C maintains a state of "1".
  • the gate circuit 161 produces a signal in which the color signals E R , E B and E G are composed in a ratio of 0.63:0.45:0.59 and their phases satisfy the equation (3).
  • This signal is applied to a band pass filter 17 having a pass band characteristic as shown in FIG. 7D to derive therefrom a chrominance signal E C .
  • the chrominance signal E C composed of color signals E R , E B and E G with the same composition ratio and phases as those of the NTSC color television signal.
  • the signal E C is delivered to a frequency converter 18.
  • the signal generator 5 produces a signal S C having an NTSC subcarrier frequency f sc and this signal S C is supplied to a frequency converter 19 together with the timing pulse T P having the frequency f s from the timing signal generator 6 to derive therefrom a signal having a frequency (f sc -f s ).
  • These signals are fed to a band pass filter 20 having a pass characteristic as shown in FIG. 7E to derive therefrom a chrominance signal E CN ' having a carrier frequency f sc which corresponds to the subcarrier frequency of the NTSC color television signal.
  • This signal E CN ' is supplied to the amplifier 15.
  • Reference numeral 21 represents a burst signal forming circuit to which the signal generator 5 supplies the signal S C of the carrier frequency f sc and a burst flag pulse B F to intermittently produce a burst signal S B having a frequency f sc which is applied to the amplifier 15.
  • the signal generator 5 also generates a composite synchronizing signal S S which is also fed to the amplifier 15.
  • the amplifier 15 produces a signal which is coincident with the NTSC color television signal.
  • the signal processing circuit of this invention is used in converting a dot-sequential color signal into an NTSC color television signal, it is not necessary to use the prior art process wherein a chromiance signal is once decoded. but the dot-sequential color signal can be converted directly into the NTSC color television signal with a substantially simplified circuit. Besides, it is not necessary for a color signal to pass through an unnecessary circuit as mentioned above and hence the color reproducibility of a picture is improved.
  • FIG. 9 shows another embodiment of this invention.
  • a consideration will be made of a case where a white color object is imaged by a color pickup device.
  • the white color will not be correctly projected on a monitor screen due to color temperature of illumination at the position of the object and the like. Therefore, it is necessary to adjust the signal levels so that the white color object will always exhibit its white color correctly on the picture screen.
  • the signal processing system of this invention is used in the aforesaid white balance control.
  • Reference numeral 22 denotes a signal processing circuit serving as a white balance control circuit.
  • An analog-signal gate circuit 221 of the processing circuit 22 is applied with a dot-sequential color signal which is similarly fed from the solid state color pickup device 4 through sample-hold circuit 8 and ⁇ -correction circuit 9.
  • the timing pulse T P (FIG. 10B) from the timing signal generator 6 is supplied to monostable multivibrators 222R, 222B and 222G to trigger them by its falling edge to derive therefrom pulses M R3 (FIG. 10C), M B3 (FIG. 10E) and M G3 (FIG.
  • the analog-signal gate circuit 221 delivers a signal in which red, blue and green color signal components are composed in a ratio of 1:1:1.
  • the output signal of the analog-signal gate circuit 221 is supplied to an NTSC conversion circuit 23 to be converted into an NTSC color signal by adjusting, for example, a synchronous detection axis and a modulation level during a process in which, for example, a chrominance signal is once synchronously-detected and the detected signal is again modulated to obtain a chrominance signal having a carrier frequency 3.58 MHz.
  • the analog-signal gate circuit 221 has derived therefrom a signal with the composition ratio of red, blue and green color signal components being 1:1:1. Therefore, the NTSC conversion circuit 23 is expected to produce no color carrier component but a luminance signal only with the result that a white color picture must be projected on the monitor screen.
  • the error voltage of red color difference signal stored in the memory circuit 28 is supplied to the monostable multivibrators 222R and 223R thereby to control the width of the pulse P R3 with its center position being kept unchanged.
  • the error voltage of blue color difference signal stored in the memory circuit 29 is also supplied to the monostable multivibrators 222B and 223B thereby to control the width of the pulse P B3 with its center position being kept unchanged.
  • the error detecting circuit 26 detects the red color and the detected signal is fed to the multivibrators 222R and 223R to reduce the width of pulse P R3 .
  • a signal obtained from the analog-signal gate circuit 221 is adapted to have a small composition ratio of its red color signal component, so that the level of red color signal becomes low to achieve the white balance.
  • the white balance control can be easily achieved by changing the pulse width only.
  • the white balance can be similarly controlled in such a manner that a variable resistor is used as the resistor of each time constant circuit in the multivibrators 222R, 223R, 222B, 223B, 222G and 223G of the processing circuit 22 and this variable resistor is adjusted by hand while a monitored picture being viewed.
  • FIG. 11 shows a further embodiment of this invention, in which 32 indicates a signal processing circuit.
  • the output signal of the color pickup device 4 is supplied to a first sample-hold circuit 30 where it is held, and an output of this first sample-hold circuit 30 is then fed to a second sample-hold circuit 31.
  • the timing pulse T P from the timing signal generator 6 is utilized to obtain a gate signal P R4 for red color signal portion by monostable multivibrators 322R and 323R, a gate signal P B4 for blue color signal portion by monostable multivibrators 322B and 323B, a gate signal P G4 for green color signal portion by monostable multivibrators 322G and 323G, respectively.
  • a composite gate signal G A from an OR circuit 324 is supplied to the second sample-hold circuit 31, so that only during an interval where the gate signal G A maintain a state of "1", the output signal from the color pickup device 4 can be sampled and held in the second sample-hold circuit 31.
  • the multivibrators 322R and 323R, 322B and 323B, and 322G and 323G are respectively applied with control signals from terminals 33R, 33B and 33G to change the widths of respective output pulses of these multivibrators thereby changing the holding duration of red, blue and green color signals in the second sample-hold circuit 31.
  • the output signal or dot-sequential color signal from the solid state color pickup device 4 is gain-controlled.
  • variable resistors or the like can be adjusted by hand to change the widths of output pulses of the multivibrators 322R through 323G.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Color Television Image Signal Generators (AREA)
  • Processing Of Color Television Signals (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)
US05/915,253 1977-06-16 1978-06-13 Signal processing system for a solid state television camera Expired - Lifetime US4200884A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP52-71544 1977-06-16
JP7154477A JPS546424A (en) 1977-06-16 1977-06-16 Signal processing method of solid pickup unit

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US4200884A true US4200884A (en) 1980-04-29

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US (1) US4200884A (ja)
JP (1) JPS546424A (ja)
CA (1) CA1124386A (ja)
DE (1) DE2826550C2 (ja)
FR (1) FR2394947A1 (ja)
GB (1) GB2000416B (ja)
NL (1) NL7806529A (ja)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4338625A (en) * 1979-12-24 1982-07-06 Sony Corporation Solid state television camera
US5282024A (en) * 1989-08-23 1994-01-25 Canon Kabushiki Kaisha White balance correction device
US20080309803A1 (en) * 2006-11-27 2008-12-18 Michiko Morita Phase adjustment device, phase adjustment method and digital camera

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5848455A (ja) * 1981-09-17 1983-03-22 Canon Inc 電荷転送素子
JPS6074791A (ja) * 1983-06-20 1985-04-27 Nec Home Electronics Ltd 単板カラーカメラ

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3512094A (en) * 1967-07-27 1970-05-12 Bell & Howell Co Electronic signal processing systems
US3936870A (en) * 1973-05-29 1976-02-03 Sony Corporation Automatic gain control for color television camera with reproduced color fidelity
US4007488A (en) * 1975-02-07 1977-02-08 Nippon Electric Co., Ltd. Solid-state color imaging apparatus having charge-coupled devices
US4071853A (en) * 1974-03-29 1978-01-31 Sony Corporation Solid state television camera
US4095254A (en) * 1975-10-17 1978-06-13 Thomson-Brandt Transcoder for color television signals

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5026378A (ja) * 1973-07-11 1975-03-19
JPS5737151B2 (ja) * 1974-08-22 1982-08-07
JPS5148928A (ja) * 1974-10-25 1976-04-27 Oki Electric Ind Co Ltd Purinta
JPS5752754B2 (ja) * 1975-02-14 1982-11-09
JPS60838B2 (ja) * 1976-05-28 1985-01-10 ソニー株式会社 カラー固体撮像装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3512094A (en) * 1967-07-27 1970-05-12 Bell & Howell Co Electronic signal processing systems
US3936870A (en) * 1973-05-29 1976-02-03 Sony Corporation Automatic gain control for color television camera with reproduced color fidelity
US4071853A (en) * 1974-03-29 1978-01-31 Sony Corporation Solid state television camera
US4007488A (en) * 1975-02-07 1977-02-08 Nippon Electric Co., Ltd. Solid-state color imaging apparatus having charge-coupled devices
US4095254A (en) * 1975-10-17 1978-06-13 Thomson-Brandt Transcoder for color television signals

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4338625A (en) * 1979-12-24 1982-07-06 Sony Corporation Solid state television camera
US5282024A (en) * 1989-08-23 1994-01-25 Canon Kabushiki Kaisha White balance correction device
US20080309803A1 (en) * 2006-11-27 2008-12-18 Michiko Morita Phase adjustment device, phase adjustment method and digital camera
US7936387B2 (en) 2006-11-27 2011-05-03 Panasonic Corporation Phase adjustment device, phase adjustment method and digital camera

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Publication number Publication date
DE2826550C2 (de) 1986-12-04
JPS546424A (en) 1979-01-18
GB2000416B (en) 1982-01-13
JPS6238909B2 (ja) 1987-08-20
CA1124386A (en) 1982-05-25
FR2394947B1 (ja) 1984-10-19
NL7806529A (nl) 1978-12-19
GB2000416A (en) 1979-01-04
DE2826550A1 (de) 1979-01-04
FR2394947A1 (fr) 1979-01-12

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